You'll have to be more specific, like what is each side, as in height, width or length. Sorry!
1 ft = 12 inches....so 10 ft = (10 * 12) = 120 inches
each strip of wall paper is 20 inches...
so 120/20 = 6 strips of wall paper are required <==
Did they give values for the letters??
1440
because yea
hehehehehehehehehee
The Answer is x=15. Good luck!